In the process of manufacturing semiconductor devices, when forming a silicide film on a diffusion layer or a gate wiring layer, the natural oxide films, which are generated on the surface of the area where the silicide film will be formed, is removed in advance. To remove such oxide films, various wet etching and dry etching methods are used.
However, when removing such oxide films, portions of other films (for example, oxide insulating films used as the STI (Shallow Trench Isolation), oxide insulating films used as the side wall film of the gate wiring, and so on) are also removed. Removal of the other films can cause failure of the semiconductor devices, such as through current leakage in the device, etc.
Similarly, during etching processes for forming a contact hole, a part of the insulation film forming the side of the contact hole is etched. Additionally, in the cases where an insulating film is formed at the bottom of the contact hole, such as a borderless contact hole, the insulating film at the bottom of the contact hole is etched, which can lead to current leakage.